Piezoelectric Actuator Control for Diesel Injection Precision
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Solution Overview
Problem
Piezoelectric actuators in fuel injection systems face challenges in precise control, particularly in maintaining precise injection processes and compensating for tolerances and ageing phenomena, due to lack of precise regulation of hydraulic cut-off and hysteresis behavior, especially in high-pressure diesel injection systems.
Innovation Solution
A method and control unit for controlling piezoelectric actuators that charge to a starting voltage, discharge to a partial lifting voltage, and then to an off-load voltage, using the partial lifting voltage as a control parameter to regulate the control valve, allowing for precise control of injection processes by adjusting the voltage gradient and frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the piezoelectric actuator is discharged directly to off-load voltage, then the injection process ends quickly, but the hydraulic cut-off cannot be precisely controlled
Solution Approach 1:
The discharge process is segmented into multiple stages: first discharging to a partial lifting voltage to achieve precise hydraulic cut-off control, then discharging to off-load voltage to complete the injection process. This segmentation allows precise control at the critical cut-off moment while maintaining overall efficiency.
Solution Approach 2:
The actuator is discharged to a partial lifting voltage before reaching off-load voltage. This preliminary action enables precise control of the hydraulic cut-off point, ensuring accurate injection termination before the final discharge to off-load voltage completes the process.
2Manufacturing precision
If the piezoelectric actuator is discharged to partial lifting voltage during discharging, then the control valve can be precisely regulated, but the discharging process becomes more complex
Solution Approach 1:
The control process utilizes changes in voltage parameters (discharging to partial lifting voltage, then to off-load voltage) to achieve precise control of the control valve. By manipulating the voltage parameter in specific stages, precise valve regulation is achieved without requiring complex mechanical adjustment mechanisms.
3Reliability
If the piezoelectric actuator is charged to starting voltage to start injection, then the injection process begins, but the minimum quantity stability cannot be ensured
Solution Approach 1:
The control process uses feedback from the partial lifting voltage measurement to adjust and stabilize the injection quantity. By monitoring the voltage during the holding time and using it as a control parameter, the system ensures minimum quantity stability and precise injection quantity control throughout the injection process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise and efficient regulation of the control valve, ensuring minimum quantity stability and accurate injection control, even in aged systems, by utilizing the partial lifting voltage as a control variable, thereby improving the overall injection process precision.
Implementation Method 1
Piezoelectric actuators are used in a wide variety of technical fields to activate a final controlling element
Data Source
AI summary
A method for controlling a piezoelectric actuator which displaces a control element of an injection valve includes the step of charging the actuator until a start voltage is reached. Subsequently, the actuator is discharged until a partial lifting voltage, which is maintained during a holding time, is reached. In the final step, the actuator is discharged until an off-load voltage is reached and a parameter which is dependent on the partial lifting voltage is used as a control variable. A desired value for the control variable is determined and the actuator is controlled in such a manner that the desired value of the control variable is maintained.